At the present time, a definite trend has formed towards smaller cellular telephones, in terms of volume and footprint. Some telephones presently being sold commercially are small enough and light enough to slip into a shirt pocket. Given the high degree of portability of such phones, consumer preference for the smaller, lighter telephones has grown considerably.
However, decreasing the size of these telephones requires the designer to balance many competing interests. For example, there is a minimum distance which must be maintained between the microphone and the speaker in the telephone design to accommodate the distance between a user's mouth and his or her ear. Telephones which do not maintain a mouth-to-ear distance of 140 mm (5.5 inches) have been considered by some users as too small for comfortable use.
There are several ways in which the cellular telephone manufacturers have attempted to balance the desire for small size with the need to maintain proper mouth-to-ear distance. One common way is to use a two-piece "flip" design, i.e., the first piece with the microphone mounted thereto (lower piece) is joined to the second piece with the speaker mounted thereto (upper piece) for pivoting movement about an axis of rotation. See U.S. Pat. No. 5,649,309. Another common solution is to use a two-piece housing with a sliding connection between the first piece with the microphone mounted thereto (lower piece) and second piece with the speaker mounted thereto (upper piece). See U.S. Pat. Nos. 5,657,370 and 5,369,788. Through the use of such designs, the competing interests of size and mouth-to-ear distance are balanced.
However, an ergonomically correct design is meaningless if functionality is affected. Therefore, the cellular telephone designer must not only design for comfort and looks, but for performance as well.
In a cellular telephone system, radio frequency signals are used to convey information, such as an audio message, from one point to another. Specifically, the cellular system is made up of a number of centralized transmitter/receiver stations, referred to as base stations, and much greater number of cellular telephone units, which are moveable relative to the base stations, referred to as mobile stations. Both the base stations and the mobile stations have antennas which can be used to transmit and receive radio frequency signals.
The performance of the cellular telephone system can be affected by obstructions between the base stations and the mobile stations that block the path of propagation of signals between the stations. For example, the path of propagation between the base station and the mobile station may be blocked by buildings, trees, mountains, or vehicles. In fact, the head of the user may also obstruct the propagation of the radio frequency signal between the mobile station and the base station.
To limit obstruction caused by the user's head, it is advantageous to have the antenna mounted as far away as possible from the user's head. Additionally, the antenna may be angled away from the user's head to further minimize the interference caused thereby to the telephone's performance. Some designs integrate both remote placement and angled placement. See U.S. Pat. No. 5,404,390.
Of course, as the size of the telephone becomes smaller, less and less room is available for placement of the antenna remotely from the user's head. Furthermore, placement of the antenna at an angle to the user's head can increase the footprint of the telephone and/or the space required to store the antenna within the telephone housing. Additionally, retraction of the antenna into the housing is complicated by the angle at which the antenna is disposed relative to the housing to which it is attached.
As one possible compromise between the competing concerns of size, mouth-to-ear distance, and telephone performance, several patents have suggested use of a flip telephone design wherein the antenna is secured to the lower portion of the telephone rather than the upper portion. U.S. Pat. No. 5,649,309 illustrates one such telephone. U.S. Pat. No. 5,706,332 illustrates a variation of the basic design wherein the antenna has been pivotably secured to the lower portion of the flip. In both designs, the antenna is disposed remotely from and at an angle to the user's head with the flip in its operative state and the antenna in its extended state.
Alternatively, U.S. Pat. No. 5,630,211 illustrates a flip telephone wherein the antenna is mounted separately from the upper and lower pieces. As shown in FIGS. 1a and 1b of the patent, when the lower portion of the flip is moved clockwise relative to the upper portion of the flip, the antenna is also moved clockwise relative to the upper portion. In particular, as shown in FIGS. 3a-3c, a pin attached to the lower portion cooperates with a slot in the antenna to move the antenna with the lower portion in a clockwise direction. To space the antenna from the lower portion of the telephone, the antenna may be moved further in a clockwise direction (see FIG. 3c). FIGS. 4a and 4b show the antenna mounted for movement with the upper portion of the telephone, rather than with the lower portion of the telephone.
While these designs allow for the spacing of the antenna from the upper (or lower) portion of the telephone to reduce the obstruction caused by the user's head, the designs typically also require several motions to configure the telephone in its operative state. For example, U.S. Pat. Nos. 5,649,309; 5,706,332 and 5,630,211 require the user to not only open and close the flip, but also to extend and retract the antenna between its operative state and its retracted or stored state. Moreover, in U.S. Pat. No. 5,630,211, because the antenna is pivotable relative to both the upper and lower pieces, the design requires an additional movement by the user in rotating the antenna away from the lower (1a, 1b) or upper (4a, 4b) portion of the telephone to provide the desired spacing between speaker and antenna.
Moreover, because of the rotary motion involved, the contacts between the antenna and the remainder of the circuitry become quite complex. Further, the contacts and the connection mechanism itself can be quite fragile, easily susceptible to damage when jarred or dropped.
To reduce the number of motions required to configure the telephone between operative and inoperative states, some flip telephones have been fitted with a spring mechanism to move the two pieces relative to each other at the push of a button. See U.S. Pat. Nos. 5,649,309 and 5,706,332. However, these spring mechanisms take up valuable space within the telephone housing, and have proven to be fragile, costly and complex to manufacture. Further, the user must be careful not to obstruct the movement of the flip, a complicated proposition with the size of the still be extended and retracted, so only a minimal conservation of motion has been achieved.
As a further alternative, Japanese Laid Open Application 7-38461 shows a phone wherein a second housing is coupled to an antenna, such that movement of the second housing relative to a first housing causes the antenna to move between a first, retracted state and a second, extended state. One of the phones shown is a flip phone, wherein the second housing is coupled to the antenna by a gear train such that movement of the second housing relative to the first housing causes the antenna to move axially between first and second states. Another of the phone has a sliding connection between the first and second housings, and the second housing has a projection which is received within a hole in the antenna to couple the antenna to the second housing such that movement of the second housing relative to the first housing causes the antenna to move axially between first and second states.
While these phones allow for the user to move the second housing and the antenna relative to the first housing using a single motion, thereby achieving an open and extended state, these phones may still have disadvantages. As stated above, it is important to maximize the distance between the antenna and the user's head. Even with the spacing between the antenna and the second housing shown, the user's head may present a significant obstacle to the propagation between the telephone and a base station.